This invention relates to an umbrella and more particularly to an improved shortenable or collapsible umbrella of the type that may be folded into four-sections when it is not in use or when it is put in storage.
Various designs of the aforesaid type of umbrella have been developed and used nowadays since they are handy as well as convenient in storage.
For enhancing the stability in its open state and reducing the size in its closed state, I have presented an umbrella with an improved rib structure in Chinese utility model application No.94203684.0, which was filed on Feb. 18, 1994, and depicted herein in FIG. 6 of the drawings.
The above umbrella can attain the effects of enhancing its stability and reduction of size. However, the rib structure of the umbrella comprises six or eight rib assemblies pivotally arranged around the crown (10) and the slider (11), and the guide ring (R) for controlling the tension wire (6) to move along beneath the rod (5) having a cross section of a reverse U shape is fixedly mounted around the intermediate portion of the rod (5). The force applied to push the slider (11) upward along the shaft (13) to change the umbrella from closed condition to open condition, or vice versa, will act to force the tension wire (6) moving remote from or toward the shaft (13) side. Since the guide ring (R) is fixedly secured to the rod (5), the friction developed between the tension wire (6) and the guide ring (R) will hinder the smooth movement of the tension wire (6). As described above, the umbrella comprises eight rib assemblies, as such the total friction developed during the opening and closing of the umbrella will be considerable, which results in difficulties in the operation of the umbrella.
The guide ring has also been used in an umbrella such as the one disclosed in Japanese laid open utility model application No.59-120912 (dated Feb. 2, 1983), where the guide ring is fixed to the inner wall of the U-shaped groove of the rod by means of caulking. This arrangement has the same problems as those in my previous design.
To my knowledge, all the guide rings being used in umbrellas for guiding the tension wire are fixedly secured either on the rods associated therewith or on the tension wire itself.
Therefore, it is the first object of the present invention to provide an umbrella with an improved rib structure that can successfully resolve the problems associated with the prior umbrella.
The second object of the present invention is to provide an umbrella which has a reduced size in the closed condition.
In accordance with the present invention, there is provided a guide ring which may move freely on the rod during the opening and closing operations of the umbrella by virtue of the movement of the tension wire. Specifically, when the friction between the guide ring and the tension wire is larger than that between the guide ring and the rod, the guide ring will follow the movement of the tension wire to move either remote from or toward the shaft side. Consequently, the force required in the operation of the opening and closing of the umbrella will be reduced, which facilitates the operation of the umbrella.
With the above objects and advantages in view, the present invention will become more clearly understood from the following detailed description of a preferred embodiment of the present invention, in connection with the accompanying drawings, of which: